There is a long history of spacecraft carrying ham radio gear, as the Space Shuttle, Mir, and the ISS have all had hams aboard with gear capable of talking to the Earth. However, this month, the ISS started operating an FM repeater that isn’t too dissimilar from a terrestrial repeater. You can see [TechMinds] video on the repeater, below.
The repeater has a 2 meter uplink and a 70 centimeter downlink. While you can use a garden variety dual-band ham transceiver to use the repeater, you’ll probably need a special antenna along with special operating techniques.
One of the problems you’ll find is that ISS moves fast enough that you will observe doppler shift in the frequencies. The video reproduces a table of frequencies you may have to move through to receive the shifting signal.
You can probably hear the ISS with a good pass with no special equipment, but [TechMinds] wasn’t able to close an actual contact in the video. But [K0LWC] got really close using a pretty standard radio setup, as you can see in the second video.
The ISS has been on the air with digital repeaters and conventional FM radio for some time. The antenna you need doesn’t have to be a huge disk. We’ve seen it done with a handheld beam antenna and a handheld radio.
Read more – via Blog – Hackaday https://hackaday.com/2020/09/10/iss-ham-radio-repeater/